New fuse box?

[JohnW2]

I presume you meant that you had grabbed a live wire while leaning on earthed parts and the RCD possibly saved your life. John has frequently asked if anyone has actually experienced this - I certainly have not.

I have indeed often asked that, and so far heard of virtually no such cases (and, even if one did hear of cases, there would be no guarantee that the person would have died in the absence of an RCD).

However, as I've been saying, there is another side to this, about which it is essentially impossible to have any statistics - relating to those people who did not suffer an electric shock, because an RCD had previously cleared a fault that ADS would not have cleared.

Having said all that, I still think it very probable that if the (vast) amount which has been spent on the purchase and installation of RCDs over the past few decades had, instead, been spent in some other safety-critical area (e.g. road safety), that the number of 'lives saved' would very probably be greater.

[For what it's worth, I'm even less convinced that the notification requirements which came with the introduction of Part P have saved (m)any lives!]

Kind Regards, John

 

[RF Lighting]

I'm struggling to think of a realistic set of circumstances where you could end up with a dangerous installation due to an earth fault which would not be cleared by ADS but would be by an RCD?

 

[JohnW2]

I'm struggling to think of a realistic set of circumstances where you could end up with a dangerous installation due to an earth fault which would not be cleared by ADS but would be by an RCD?

I may be wrong, but I would doubt that you would deny that there are countless situations in which attached (e.g. 'plugged in') equipment can develop L-E faults which would trip an RCD but would not invoke ADS (that's probably the most common situation with 'appropriate' RCD trips), so I guess it comes down to what you would classify as a 'dangerous installation'.

What you may be thinking of is that, if one's 'proper design/installation' has resulted in a perfect equipotential zone, then it "doesn't really matter" (**) if all the exposed-c-ps remain (undetected) indefinitely at a relatively high potential relative to true earth - but I have to say that (illogical though it may be) I wouldn't want to be the person living with that situation!

[** except for someone with one foot/hand in the property and one foot/hand outside -or the person touching the oft-cited 'earthed' outside tap! ]

Kind Regards, John

 

[RF Lighting]

I know there are plenty of faults which trip RCDs, but the majority of them are not going to present a danger. A lighting circuit which leaks 60mA to earth will trip an RCD but would not present a hazard to the user were that circuit not on RCD.

Don't get me wrong, RCDs have their place, but slapping one on every circuit without giving any thought as to whether that is really the best design is what I have an issue with.

 

[JohnW2]

I know there are plenty of faults which trip RCDs, but the majority of them are not going to present a danger. A lighting circuit which leaks 60mA to earth will trip an RCD but would not present a hazard to the user were that circuit not on RCD.

True, but if one applies too much 'common sense', a lot of the things we do in the name of 'reducing danger' are probably not strictly necessary. As I said, in a building which has been designed and installed as a perfect equipotential zone, one doesn't really have to worry about the potential of exposed-c-ps relative to true earth (or anything else). Indeed, in that situation one doesn't even need ADS to protect people against electric shock - one needs ADS only to protect cables/accessories, and hence eliminate/reduce risks of fire.

Don't get me wrong, RCDs have their place, but slapping one on every circuit without giving any thought as to whether that is really the best design is what I have an issue with.

Agreed, but I suspect that we are only one or two editions of the regs away from RCD protection being required for every circuit! Even today, I doubt that (m)any would install a separate circuit for bathroom lighting just so that the remainder of the lighting in that property (at least, on the same floor) could be left without RCD protection!

Kind Regards, John

 

[RF Lighting]

Use an RCD FCU for the bathroom and then the 3a fuse required for the fan is achieved at the same time

 

[scousespark]

The rest of us did (and that was all sockets including those not likely to be used outside) and also electric showers etc.

The OP said the extension was added in 2006. To comply with the 16th edition fitting socket outlets with built in RCD protection near the door was enough. He never mentioned a new CU.

 

[JohnW2]

The OP said the extension was added in 2006. To comply with the 16th edition fitting socket outlets with built in RCD protection near the door was enough. He never mentioned a new CU.

Indeed, but the point Risteard has been labouring is that he claims that 95% of the electricians he knew RCD-protected all (new) sockets at that time, even though he concedes that the 16th ed. did not require it.

I can but presume that he was talking about 95% of a different population of electricians from the population with which I (and, I suspect, others) was familiar.

Kind Regards, John

 

[Taylortwocities]

Yes, he is talking about a part of the UK that is called Northern Ireland.

It would seem that it's somewhat different there.

 

[JohnW2]

Yes, he is talking about a part of the UK that is called Northern Ireland. It would seem that it's somewhat different there.

Indeed - that was, of course, my point!

Kind Regards, John

 

[John D v2.0]

True, but if one applies too much 'common sense', a lot of the things we do in the name of 'reducing danger' are probably not strictly necessary. As I said, in a building which has been designed and installed as a perfect equipotential zone, one doesn't really have to worry about the potential of exposed-c-ps relative to true earth (or anything else).

Well I connected all my bonding to the live, then I don't need to worry about accidentally touching a live wire

 

[JohnW2]

Well I connected all my bonding to the live, then I don't need to worry about accidentally touching a live wire

.... As far as people totally within a building are concerned, if it is constituted as a true equipotential zone, then it doesn't matter whether everything touchable within the building is at 0V, 230V or 2,300V above earth potential ... but your plan would all go wrong if there were any significant extraneous-c-ps

Kind Regards, John

 

[scousespark]

Yes, he is talking about a part of the UK that is called Northern Ireland.

It would seem that it's somewhat different there.

I think the confusion is between rewiring/CU changes and wiring the extension. For rewires and CU changes it was common practice to RCD protect ground floor socket circuits. I don't recall protecting upstairs circuits. To wire the extension, I don't think we insisted on RCD protection. We were not protecting the cable at that time, just equipment. Maybe Risteard and his colleaugues worked differently.

 

[deadshort]

Odd! as most extensions are on the ground floor and lead to outside

DS

 

[scousespark]

Odd! as most extensions are on the ground floor and lead to outside

DS

I made 2 points.
To change that CU, we would have RCD protected the shower and any downstairs socket circuits. I don't recall protecting the upstairs socket circuits.

It was possible to wire up that extension without a board change. FYI some extensions have more than one story.